Universal dependence of the reflection coefficient of a stimulated-Brillouin-scattering mirror on the excess above the threshold

Theoretical calculations are reported of the dependences of the nonlinear energy reflection coefficient of a stimulated-Brillouin-scattering (STBS) mirror R_w(α) on the excess a of the energy of laser pulses above the threshold under steady-state and transient conditions. It is shown that in the absence of stray effects the function R_w(α) for quasimonochromatic focused radiation is practically universal and depends weakly on the chemical composition of the nonlinear medium, experimental geometry, profile and duration of the pump pulses. The experimental results are in satisfactory agreement with theoretical dependences R_w(α) predicted for the steady-state and transient STBS of single-mode and multimode light beams.